1. Field of the Invention
The present invention relates generally to an electrical power circuit breaker. More particularly, the invention encompasses an electrical power modular circuit breaker. Even more particularly, the invention relates to electrical power circuit breakers that integrate overload, arc fault, and ground fault detection and interruption.
2. Description of Related Art
U.S. Pat. No. 4,641,217 (Robert A. Morris, et al.), describes a two pole ground fault circuit breaker is provided by the attachment of a power supply module and a second single pole circuit breaker module to a completely assembled single pole ground fault circuit breaker. Electrical interconnection between the signal processor circuit within the single pole ground fault circuit breaker module and the second pole is made by a first pair of conductors. Interconnection between the power supply module and the single pole within the ground fault circuit breaker is provided by a separate pair of conductors.
U.S. Pat. No. 5,321,574 (John R. Patrick, et al.) illustrates a circuit breaker/surge arrestor package for plug-in installation in the space of two standard one-inch openings in a contemporary residential load center. The electrical and thermal characteristics of the components are selected such that a threshold of a substantially continuous current through a Metal Oxide Varistor in the surge arrestor causes the circuit breaker to trip magnetically before being able to trip thermally.
U.S. Pat. No. 5,483,211 (Melvin A. Carrodus, et al.) describes a miniature circuit breaker with two thermal-magnetic poles has an electronic trip device providing ground fault, and sputtering arc fault (if desired), protection located entirely in a large central compartment of a molded housing between compartments housing the two mechanical poles. The molded housing is assembled from a top base and top cover forming a compartment for the thermal-magnetic trip device of the first pole, and a bottom cover and a bottom base forming the compartment for the second mechanical pole. A hollow center piece mates with the top and bottom bases to form the single, large electronics compartment.
Examples of a two pole ground fault circuit breaker are provided in U.S. Pat. Nos. 5,483,211 (211 patent) and 4,641,217 (217 patent). These breakers include common mechanism that include thermal and magnetic components to provide overload and instantaneous trip functions that protect circuits. Insulated molded housings are used to enclose and separate the mechanism poles from the electrical components. Electronic ground fault detection is included in these circuit breakers. The overall breaker size is standard so that they plug or bolt into two adjacent positions of a load center or panel board.
The molded housings for the two pole ground fault circuit breaker for '217 patent are basically two molded housings for each thermal/magnetic mechanism. The molded housing includes an open compartment. The bottom open compartment is for the mechanism while the other upper open compartment is for part of the electrical components for ground fault detection. When the mechanism poles are assembled, the two upper open compartments come together to form a compartment containing the electronics for the ground fault detection sandwiched between the two mechanism poles. For the '211 patent, the molded housings are basically two molded housings for each thermal/magnetic mechanism. Each bottom mold contains an open compartment for the mechanism. For one mechanism, an upper housing encloses the mechanism and provides another open compartment, opposite side of the housing, for part of the ground fault electronics. A separate open molded housing, containing the outside dimensions as the mechanism molded housings except with no inner wall, is used to form the remaining compartment for the electronics. When the mechanism poles are assembled with the open molded housing, a compartment is formed containing the electronics for the ground fault detection sandwiched between the two mechanism poles.
Both the '211 and the '217 patents include electronics for ground fault by providing neutral to ground and line to ground fault detection. These circuits require a double wound solenoid located in the electronic compartment between the two thermal/magnetic mechanical poles.
The splitting of the electronic compartment as described in both '211 and '217 patents requires additional assembly effort with loose parts. This complicates assembling of the two pole circuit breakers at final assembly. In the '217 and '211 patents, the electronics enclosed in the center compartment includes ground fault detection only.